DISTRIBUTED ENERGETICS OF BOREAL FOREST SNOWMELT
Faria, Derek Andrew
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The energetics of snowmelt under boreal forest canopies in central Saskatchewan were examined with respect to the influence of forest canopy structure on the snow cover depletionrate. The distribution of snow water equivalent was examined prior to melt and during melt in five distinct boreal forest environments, and the distribution of melt rate was quantified for each environment. The frequency distribution of snow water equivalent was found to fit a log-normal distribution. The distribution of snowmelt energy below forest canopies was not uniform but inversely related to the distribution of snow water equivalent, with shallows now receiving higher fluxes of melt energy. Distribution of melt energy therefore promoted an earlier depletion of snowcover than if melt energy were uniform. A more variable distribution of melt energy was produced by higher variance in canopy structure or lower canopy density than that produced by more uniform canopy structure or higher canopy density. While higher canopy density resulted in higher variability in snow water equivalent, and in open environments a higher variability in snow water equivalent resulted in an earlier depletion of snowcover, forest canopies reduce the energy available for melt. Therefore lower canopy density generally results in more energy for snowmelt and a more variable distribution of melt energy, leading to earlier depletion of snowcover. The rate of depletion therefore depends on available melt energy and on the distributions of melt energy and of snow water equivalent, all of which are influenced by canopy structure. Depletion was found to occur first in a burn and clear-cut, then in a mixed-wood and pine,and finally in a black spruce.